The present invention relates to the separation of compounds using tagging moieties including varying numbers of repeat units, and particularly, to the use of tagging moieties including repeat units that increase affinity of the tag for a stationary support (by, for example, changing the polarity, the hydrophilicity, the lipophilicity, or the charge of the tag) in a stepwise manner as the number of repeat units increases.
References set forth herein may facilitate understanding of the present invention or the background of the present invention. Inclusion of a reference herein, however, is not intended to and does not constitute an admission that the reference is available as prior art with respect to the present invention.
Solid phase chemical synthesis methods revolutionized protein and polynucleotide synthesis and are now an important method for small molecule chemical discovery. The benefits of employing solid support methods include the ease of first-pass purification of the tethered products and the possibility of generating very large libraries through systematic diversification strategies. These benefits come with a cost, however. For example, reaction conditions that have been developed for homogeneous (“solution phase”) reactions can require substantial re-optimization for use on solid supports. Also, some solution phase reactions are not transferable to solid phase because required temperatures and/or pressures, or the need to have rapidly diffusing reactive intermediates, may be incompatible with high molecular weight supports. See, for example, Honigfort, M. E.; Brittain, W. J.; Bosanac, T.; Wilcox, C. S. Macromolecules, 2002, 35, 4849-4851. Moreover, monitoring reaction progress and characterizing products still bound to the support is challenging. See, for example, Yan, B. Acc. Chem. Res., 1998, 31, 621-630. Expensive, specialized equipment is often employed and scale-up of the optimized solid phase process may not be feasible.
To circumvent some of these difficulties with solid phase methods, researchers have pursued alternative solution phase methods such as liquid phase combinatorial synthesis, indexed combinatorial libraries, template-based libraries, precipitons, and fluorous mixture synthesis (FMS). See, for example, Han, H.; Wolfe, M. M.; Brenner, S.; Janda, K. D. Proc. Natl. Acad. Sci. USA, 1995, 92, 6419-6423. (b) Gravert, D. J.; Janda, K. D., Chem. Rev., 1997, 97, 489-509; Pirrung, M. C.; Chen, J., J. Am. Chem. Soc., 1995, 117, 1240-1245; Pirrung, M. C.; Chau, J. H-L.; Chen, J., Chem. Biol., 1995, 2, 621-626; Cheng, S.; Tarby, C. M.; Comer, D. D.; Williams, J. P.; Caporale, L. H.; Myers, P. L.; Boger, D. L, Bio. Med. Chem., 1996, 4, 727-737; Cheng, S.; Comer, D. D.; Williams, J. P.; Myers, P. L.; Boger, D. L., J. Am. Chem. Soc., 1996, 118, 2567-2573; Boger, D. L.; Tarby, C. M.; Comer, D. D.; Myers, P. L.; Caporale, L. H., J. Am. Chem. Soc., 1996, 118, 2109-2110; Bosanac, T.; Yang, J. M.; Wilcox C. S. Angew. Chem. Int. Ed. Eng., 2001, 40, 1875-1879; Bosanac, T.; Wilcox, C. S. J. Am. Chem. Soc., 2002, 124, 4194-4195; Luo, Z; Zhang, Q.; Oderaotoshi, Y.; Curran, D. P., Science, 2001, 291, 1766-1769; Curran, D. P.; Oderaotoshi, Y., Tetrahedron, 2001, 57, 5243-5253; Curran, D. P.; Furukawa, T., Org. Lett., 2002, 4, 2233-2235; Zhang, Q.; Rivkin, A.; Curran, D. P., J. Am. Chem. Soc., 2002, 124, 5774-5781; and U.S. Pat. No. 6,749,756.
In several embodiments of fluorous mixture synthesis (as disclosed, for example, in U.S. Pat. No. 6,749,756), substrates attached to fluorous sorting tags of differing fluorous nature/fluorine content are mixed, taken through a certain number of reactions as a mixture, and demixed (that is, separated) using a fluorous separation technique. The fluorous mixture synthesis approach to accelerated chemical synthesis has significant promise. An enabling characteristic of fluorous tags used for chromatographic separations is the predictable incremental increase in retention time with increasing fluorocarbon chain length.
U.S. Pat. No. 6,749,756 also discloses a general tagging scheme wherein a mixture of tagged products is separated by a separation technique based upon or complementary to differences in the tagging moieties. In addition to tags which differ in fluorous nature, U.S. Pat. No. 6,749,756 further discloses separations using tags differing in total charge, tags differing in size (for example, oligomers, dendrimers and polymers of differing length), and tags differing in polarity (for example, linear hydrocarbons of differing lengths, which decrease in polarity with increasing length).
Given the benefit that tagging methodologies can bring to chemical synthesis and separation, it is desirable to develop additional and/or complementary tags and tagging methods.